This invention relates generally to acousto-optic waveguides, and particularly to acousto-optic waveguides of the type employing a thin sheet of optical glass.
In accordance with the Bragg Defraction Theory, a spatially-coherent, substantially monochromic light beam incident upon sound waves at a particular angle, which angle is dependent upon the wavelength of the light and sound, is deflected by the sound waves at this same angle. Thus when light and sound interact at the Bragg angle, the traveling sound waves act as if they were moving mirrors. By altering the frequency of sound wave propagation, a beam of coherent light incident upon the traveling sound waves may itself be deflected.
Today there exist several types of acousto-optic devices which utilize the just described light and sound interaction phenomenon. Among these are acousto-optic beam deflectors and traveling lens devices. Each of these types of devices employ a waveguide in which light and sound interaction occurs. In some cases the waveguide may be fairly large and employ an optically clear liquid such as water housed within a transparent casing. In other cases however the waveguide should be very thin such as in the order as several tens of mils thickness for effective device operation. Waveguides of this order of thickness cannot practically be produced to encase liquids. Thus these types are ordinarily composed of an optically clear, solid sheet of glass.
Heretofore, thin glass type acousto-optic waveguides have met with only limited success due to their low power handling capabilities. Being brittle and of thin configuration, their tensile strength is quite low. Even when held firmly in position along a plane, they have tended to fracture or to shatter completely whenever an acoustic wave is impressed thereon having an amplitude in excess of the waveguide tensile strength.
Accordingly it is a general object of the present invention to provide a ruggedized acousto-optic waveguide.
More specifically, it is an object of the invention to provide a ruggedized acoustic-optic waveguide of the type comprised of a thin sheet of optically clear glass.
Another object of the invention is to provide a ruggedized acoustic-optic waveguide of the type described which is capable of guiding relatively high power acoustic waves for a given waveguide size.
Yet another object of the invention is to provide a ruggedized acoustic-optic waveguide of the type described with means for adjusting the power handling capability of the waveguide.
Still another object of the invention is to provide a ruggedized acoustic-optic waveguide of the type described which is relatively simple to construct and adjust.